/* -------------------------------------------------------------------------
 *
 * initsplan.cpp
 *	  Target list, qualification, joininfo initialization routines
 *
 * Portions Copyright (c) 2020 Huawei Technologies Co.,Ltd.
 * Portions Copyright (c) 1996-2012, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *	  src/gausskernel/optimizer/plan/initsplan.cpp
 *
 * -------------------------------------------------------------------------
 */
#include "postgres.h"
#include "knl/knl_variable.h"

#include "catalog/pg_namespace.h"
#include "catalog/pg_type.h"
#include "pgxc/pgxc.h"
#include "nodes/nodeFuncs.h"
#include "optimizer/clauses.h"
#include "optimizer/joininfo.h"
#include "optimizer/pathnode.h"
#include "optimizer/paths.h"
#include "optimizer/placeholder.h"
#include "optimizer/planmain.h"
#include "optimizer/planner.h"
#include "optimizer/prep.h"
#include "optimizer/restrictinfo.h"
#include "optimizer/streamplan.h"
#include "optimizer/var.h"
#include "parser/parsetree.h"
#include "rewrite/rewriteManip.h"
#include "utils/lsyscache.h"
#include "catalog/index.h"
#include "catalog/pg_amop.h"

/* Elements of the postponed_qual_list used during deconstruct_recurse */
typedef struct PostponedQual
{
   Node       *qual;           /* a qual clause waiting to be processed */
   Relids      relids;         /* the set of baserels it references */
} PostponedQual;
static void extract_lateral_references(PlannerInfo *root, RelOptInfo *brel, Index rtindex);
static List* deconstruct_recurse(
    PlannerInfo* root, Node* jtnode, bool below_outer_join, Relids* qualscope, Relids* inner_join_rels, List **postponed_qual_list, Relids* non_keypreserved = NULL);
static SpecialJoinInfo* make_outerjoininfo(
    PlannerInfo* root, Relids left_rels, Relids right_rels, Relids inner_join_rels, JoinType jointype, List* clause);
static bool check_outerjoin_delay(PlannerInfo* root, Relids* relids_p, Relids* nullable_relids_p, bool is_pushed_down);
static bool check_equivalence_delay(PlannerInfo* root, RestrictInfo* restrictinfo);
static bool check_redundant_nullability_qual(PlannerInfo* root, Node* clause);
static void check_mergejoinable(RestrictInfo* restrictinfo);

/*****************************************************************************
 *
 *	 JOIN TREES
 *
 *****************************************************************************/
/*
 * add_base_rels_to_query
 *
 *	  Scan the query's jointree and create baserel RelOptInfos for all
 *	  the base relations (ie, table, subquery, and function RTEs)
 *	  appearing in the jointree.
 *
 * The initial invocation must pass root->parse->jointree as the value of
 * jtnode.	Internally, the function recurses through the jointree.
 *
 * At the end of this process, there should be one baserel RelOptInfo for
 * every non-join RTE that is used in the query.  Therefore, this routine
 * is the only place that should call build_simple_rel with reloptkind
 * RELOPT_BASEREL.	(Note: build_simple_rel recurses internally to build
 * "other rel" RelOptInfos for the members of any appendrels we find here.)
 */
void add_base_rels_to_query(PlannerInfo* root, Node* jtnode, Bitmapset** checkDuplicate)
{
    if (jtnode == NULL)
        return;
    if (IsA(jtnode, RangeTblRef)) {
        int varno = ((RangeTblRef*)jtnode)->rtindex;

        if (!bms_is_member(varno, *checkDuplicate)) {
            (void)build_simple_rel(root, varno, RELOPT_BASEREL);
            *checkDuplicate = bms_add_member(*checkDuplicate, varno);
        }
    } else if (IsA(jtnode, FromExpr)) {
        FromExpr* f = (FromExpr*)jtnode;
        ListCell* l = NULL;

        foreach (l, f->fromlist)
            add_base_rels_to_query(root, (Node*)lfirst(l), checkDuplicate);
    } else if (IsA(jtnode, JoinExpr)) {
        JoinExpr* j = (JoinExpr*)jtnode;

        add_base_rels_to_query(root, j->larg, checkDuplicate);
        add_base_rels_to_query(root, j->rarg, checkDuplicate);
    } else {
        ereport(ERROR,
            (errmodule(MOD_OPT),
                errcode(ERRCODE_UNRECOGNIZED_NODE_TYPE),
                errmsg("unrecognized node type when add base_rels to query: %d", (int)nodeTag(jtnode))));
    }
}

/*****************************************************************************
 *
 *	 TARGET LISTS
 *
 *****************************************************************************/
/*
 * build_base_rel_tlists
 *	  Add targetlist entries for each var needed in the query's final tlist
 *	  to the appropriate base relations.
 *
 * We mark such vars as needed by "relation 0" to ensure that they will
 * propagate up through all join plan steps.
 */
void build_base_rel_tlists(PlannerInfo* root, List* final_tlist)
{
    List* tlist_vars = pull_var_clause((Node*)final_tlist, PVC_RECURSE_AGGREGATES, PVC_INCLUDE_PLACEHOLDERS);

    if (tlist_vars != NIL) {
        add_vars_to_targetlist(root, tlist_vars, bms_make_singleton(0), true);
        list_free_ext(tlist_vars);
    }
}

/*
 * add_vars_to_targetlist
 *	  For each variable appearing in the list, add it to the owning
 *	  relation's targetlist if not already present, and mark the variable
 *	  as being needed for the indicated join (or for final output if
 *	  where_needed includes "relation 0").
 *
 *	  The list may also contain PlaceHolderVars.  These don't necessarily
 *	  have a single owning relation; we keep their attr_needed info in
 *	  root->placeholder_list instead.  If create_new_ph is true, it's OK
 *	  to create new PlaceHolderInfos, and we also have to update ph_may_need;
 *	  otherwise, the PlaceHolderInfos must already exist, and we should only
 *	  update their ph_needed.  (It should be true before deconstruct_jointree
 *	  begins, and false after that.)
 */
void add_vars_to_targetlist(PlannerInfo* root, List* vars, Relids where_needed, bool create_new_ph)
{
    ListCell* temp = NULL;

    AssertEreport(!bms_is_empty(where_needed), MOD_OPT, "bms should not be null");

    foreach (temp, vars) {
        Node* node = (Node*)lfirst(temp);

        if (IsA(node, Var)) {
            Var* var = (Var*)node;
            RelOptInfo* rel = find_base_rel(root, var->varno);
            int attno = var->varattno;
            if (bms_is_subset(where_needed, rel->relids))
                continue;

            AssertEreport(attno >= rel->min_attr && attno <= rel->max_attr, MOD_OPT, "attno is out of range");
            attno -= rel->min_attr;
            if (rel->attr_needed[attno] == NULL) {
                /* Variable not yet requested, so add to rel's targetlist */
                /* XXX is copyObject necessary here? */
                rel->reltarget->exprs = lappend(rel->reltarget->exprs, copyObject(var));
            }
            rel->attr_needed[attno] = bms_add_members(rel->attr_needed[attno], where_needed);
        } else if (IsA(node, PlaceHolderVar)) {
            PlaceHolderVar* phv = (PlaceHolderVar*)node;
            PlaceHolderInfo* phinfo = find_placeholder_info(root, phv, create_new_ph);

            phinfo->ph_needed = bms_add_members(phinfo->ph_needed, where_needed);
        } else {
            ereport(ERROR,
                (errmodule(MOD_OPT),
                    errcode(ERRCODE_UNRECOGNIZED_NODE_TYPE),
                    errmsg("unrecognized node type when add vars to targetlist: %d", (int)nodeTag(node))));
        }
    }
}



/*****************************************************************************
 *
 *   LATERAL REFERENCES
 *
 *****************************************************************************/
void find_lateral_references(PlannerInfo *root)
{
    int rti = 0;

    /* We need do nothing if the query contains no LATERAL RTEs */
    if (!root->hasLateralRTEs) {
        return;
    }

    /*
    * Examine all baserels (the rel array has been set up by now).
    */
    for (rti = 1; rti < root->simple_rel_array_size; rti++) {
        RelOptInfo *brel = root->simple_rel_array[rti];

        /* there may be empty slots corresponding to non-baserel RTEs */
        if (brel == NULL) {
            continue;
        }

        Assert(brel->relid == (Index)rti);     /* sanity check on array */

        /* ignore RTEs that are "other rels" */
        if (brel->reloptkind != RELOPT_BASEREL) {
            continue;
        }

        extract_lateral_references(root, brel, rti);
    }
}

static void
extract_lateral_references(PlannerInfo *root, RelOptInfo *brel, Index rtindex)
{
    RangeTblEntry *rte = root->simple_rte_array[rtindex];
    List *vars = NIL;
    List *newvars = NIL;
    Relids where_needed = NULL;
    ListCell *lc = NULL;

    /* No cross-references are possible if it's not LATERAL */
    if (!rte->lateral) {
        return;
    }

    /* Fetch the appropriate variables */
    if (rte->rtekind == RTE_SUBQUERY) {
        vars = pull_vars_of_level((Node *)rte->subquery, 1);
    } else if (rte->rtekind == RTE_FUNCTION) {
        vars = pull_vars_of_level(rte->funcexpr, 0);
    } else if (rte->rtekind == RTE_VALUES) {
        vars = pull_vars_of_level((Node *)rte->values_lists, 0);
    } else {
        return;
    }

    if (vars == NIL) {
        return;
    }

    /* Copy each Var (or PlaceHolderVar) and adjust it to match our level */
    newvars = NIL;
    foreach(lc, vars) {
        Node   *node = (Node *)lfirst(lc);

        node = (Node *)copyObject(node);
        if (IsA(node, Var)) {
             Var    *var = (Var *)node;

             /* Adjustment is easy since it's just one node */
            var->varlevelsup = 0;
        } else if (IsA(node, PlaceHolderVar)) {
            PlaceHolderVar *phv = (PlaceHolderVar *)node;
            int levelsup = phv->phlevelsup;

            /* Have to work harder to adjust the contained expression too */
            if (levelsup != 0) {
                IncrementVarSublevelsUp(node, -levelsup, 0);
            }

           /*
            * It's sufficient to set phlevelsup = 0, because we call
            * add_vars_to_targetlist with create_new_ph = false (as we must,
            * because deconstruct_jointree has already started); therefore
            * nobody is going to look at the contained expression to notice
            * whether its Vars have the right level.
            */
            if (levelsup > 0) {
                phv->phexpr = preprocess_phv_expression(root, phv->phexpr);
            }
        } else {
            ereport(ERROR,
                    (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                    errmsg("expected Var or PlaceHolderVar, others unsupported. ")));
        }

        newvars = lappend(newvars, node);
    }

    list_free(vars);

    /*
    * We mark the Vars as being "needed" at the LATERAL RTE.  This is a bit
    * of a cheat: a more formal approach would be to mark each one as needed
    * at the join of the LATERAL RTE with its source RTE.  But it will work,
    * and it's much less tedious than computing a separate where_needed for
    * each Var.
    */
    where_needed = bms_make_singleton(rtindex);

    /* Push the Vars into their source relations' targetlists */
    add_vars_to_targetlist(root, newvars, where_needed, true);

    /* Remember the lateral references for create_lateral_join_info */
    brel->lateral_vars = newvars;
}

/*
 * create_lateral_join_info
 *   For each LATERAL subquery, create LateralJoinInfo(s) and add them to
 *   root->lateral_info_list, and fill in the per-rel lateral_relids sets.
 *
 * This has to run after deconstruct_jointree, because we need to know the
 * final ph_eval_at values for referenced PlaceHolderVars.
 */
void
create_lateral_join_info(PlannerInfo *root)
{
    int rti;
    ListCell *lc = NULL;

    /* We need do nothing if the query contains no LATERAL RTEs */
    if (!root->hasLateralRTEs)
        return;

    /*
     * Examine all baserels (the rel array has been set up by now).
     */
    for (rti = 1; rti < root->simple_rel_array_size; rti++) {
        RelOptInfo *brel = root->simple_rel_array[rti];
        Relids      lateral_relids;

        /* there may be empty slots corresponding to non-baserel RTEs */
       if (brel == NULL)
            continue;

        Assert(brel->relid == (Index)rti);     /* sanity check on array */

        /* ignore RTEs that are "other rels" */
        if (brel->reloptkind != RELOPT_BASEREL)
            continue;

        lateral_relids = NULL;

       /* consider each laterally-referenced Var or PHV */
        foreach(lc, brel->lateral_vars) {
            Node   *node = (Node *) lfirst(lc);

            if (IsA(node, Var)) {
                Var *var = (Var *) node;
                add_lateral_info(root, bms_make_singleton(var->varno), brel->relids);
                lateral_relids = bms_add_member(lateral_relids, var->varno);
            } else if (IsA(node, PlaceHolderVar)) {
                PlaceHolderVar *phv = (PlaceHolderVar *) node;
                PlaceHolderInfo *phinfo = find_placeholder_info(root, phv, false);

                add_lateral_info(root, phinfo->ph_eval_at, brel->relids);
                lateral_relids = bms_add_members(lateral_relids,
                                                phinfo->ph_eval_at);
            } else {
                Assert(false);
            }
        }

        /* We now know all the relids needed for lateral refs in this rel */
        if (bms_is_empty(lateral_relids))
            continue;           /* ensure lateral_relids is NULL if empty */
        brel->lateral_relids = lateral_relids;
    }

    /*
     * Now check for lateral references within PlaceHolderVars, and make
     * LateralJoinInfos describing each such reference.  Unlike references in
     * unflattened LATERAL RTEs, the referencing location could be a join.
     */
    foreach(lc, root->placeholder_list) {
        PlaceHolderInfo *phinfo = (PlaceHolderInfo *) lfirst(lc);
        Relids      eval_at = phinfo->ph_eval_at;
       
        if (phinfo->ph_lateral != NULL) {
            List *vars = pull_var_clause((Node *) phinfo->ph_var->phexpr,
                PVC_RECURSE_AGGREGATES, PVC_INCLUDE_PLACEHOLDERS);
            ListCell   *lc2;

            foreach(lc2, vars) {
                Node       *node = (Node *) lfirst(lc2);
                if (IsA(node, Var)) {
                    Var        *var = (Var *) node;
                    if (!bms_is_member(var->varno, eval_at))
                        add_lateral_info(root,
                                         bms_make_singleton(var->varno),
                                         eval_at);
                } else if (IsA(node, PlaceHolderVar)) {
                    PlaceHolderVar *other_phv = (PlaceHolderVar *) node;
                    PlaceHolderInfo *other_phi;
       
                    other_phi = find_placeholder_info(root, other_phv,
                                                      false);
                    if (!bms_is_subset(other_phi->ph_eval_at, eval_at))
                        add_lateral_info(root, other_phi->ph_eval_at, eval_at);
                    } else {
                        Assert(false);
                }
            }
            list_free(vars);
        }
    }

    /* If we found no lateral references, we're done. */
    if (root->lateral_info_list == NIL)
        return;

    /*
     * Now that we've identified all lateral references, make a second pass in
     * which we mark each baserel with the set of relids of rels that
     * reference it laterally (essentially, the inverse mapping of
     * lateral_relids).  We'll need this for join_clause_is_movable_to().
     *
     * Also, propagate lateral_relids and lateral_referencers from appendrel
     * parent rels to their child rels.  We intentionally give each child rel
     * the same minimum parameterization, even though it's quite possible that
     * some don't reference all the lateral rels.  This is because any append
     * path for the parent will have to have the same parameterization for
     * every child anyway, and there's no value in forcing extra
     * reparameterize_path() calls.  Similarly, a lateral reference to the
     * parent prevents use of otherwise-movable join rels for each child.
     */
    for (rti = 1; rti < root->simple_rel_array_size; rti++) {
        RelOptInfo *brel = root->simple_rel_array[rti];
        Relids      lateral_referencers;
       
        if (brel == NULL)
            continue;
        if (brel->reloptkind != RELOPT_BASEREL)
            continue;
       
        /* Compute lateral_referencers using the finished lateral_info_list */
        lateral_referencers = NULL;
        foreach(lc, root->lateral_info_list) {
            LateralJoinInfo *ljinfo = (LateralJoinInfo *) lfirst(lc);
            if (bms_is_member(brel->relid, ljinfo->lateral_lhs))
                lateral_referencers = bms_add_members(lateral_referencers,
                                                      ljinfo->lateral_rhs);
            }
        brel->lateral_referencers = lateral_referencers;

        /*
         * If it's an appendrel parent, copy its lateral_relids and
         * lateral_referencers to each child rel.
         */
        if (root->simple_rte_array[rti]->inh) {
            foreach(lc, root->append_rel_list) {
                AppendRelInfo *appinfo = (AppendRelInfo *) lfirst(lc);
                RelOptInfo *childrel;
                if (appinfo->parent_relid != rti)
                    continue;
                childrel = root->simple_rel_array[appinfo->child_relid];
                Assert(childrel->reloptkind == RELOPT_OTHER_MEMBER_REL);
                Assert(childrel->lateral_relids == NULL);
                childrel->lateral_relids = brel->lateral_relids;
                Assert(childrel->lateral_referencers == NULL);
                childrel->lateral_referencers = brel->lateral_referencers;
            }
        }
    }
}

/*
 * add_lateral_info
 *     Add a LateralJoinInfo to root->lateral_info_list, if needed
 *
 * We suppress redundant list entries.  The passed lhs set must be freshly
 * made; we free it if not used in a new list entry.
 */
void add_lateral_info(PlannerInfo *root, Relids lhs, Relids rhs)
{
    LateralJoinInfo *ljinfo;
    ListCell   *lc;
    
    /* Sanity-check the input */
    Assert(!bms_is_empty(lhs));
    Assert(!bms_is_empty(rhs));
    Assert(!bms_overlap(lhs, rhs));
    
    /*
     * The input is redundant if it has the same RHS and an LHS that is a
     * subset of an existing entry's.  If an existing entry has the same RHS
     * and an LHS that is a subset of the new one, it's redundant, but we
     * don't trouble to get rid of it.  The only case that is really worth
     * worrying about is identical entries, and we handle that well enough
     * with this simple logic.
     */
    foreach(lc, root->lateral_info_list) {
        ljinfo = (LateralJoinInfo *) lfirst(lc);
        if (bms_equal(rhs, ljinfo->lateral_rhs) &&
            bms_is_subset(lhs, ljinfo->lateral_lhs))
            return;
    }
    
    /* Not there, so make a new entry */
    ljinfo = makeNode(LateralJoinInfo);
    ljinfo->lateral_lhs = bms_copy(lhs);
    ljinfo->lateral_rhs = bms_copy(rhs);
    root->lateral_info_list = lappend(root->lateral_info_list, ljinfo);
}



/*****************************************************************************
 *
 *	  JOIN TREE PROCESSING
 *
 *****************************************************************************/
/*
 * deconstruct_jointree
 *	  Recursively scan the query's join tree for WHERE and JOIN/ON qual
 *	  clauses, and add these to the appropriate restrictinfo and joininfo
 *	  lists belonging to base RelOptInfos.	Also, add SpecialJoinInfo nodes
 *	  to root->join_info_list for any outer joins appearing in the query tree.
 *	  Return a "joinlist" data structure showing the join order decisions
 *	  that need to be made by make_one_rel().
 *
 * The "joinlist" result is a list of items that are either RangeTblRef
 * jointree nodes or sub-joinlists.  All the items at the same level of
 * joinlist must be joined in an order to be determined by make_one_rel()
 * (note that legal orders may be constrained by SpecialJoinInfo nodes).
 * A sub-joinlist represents a subproblem to be planned separately. Currently
 * sub-joinlists arise only from FULL OUTER JOIN or when collapsing of
 * subproblems is stopped by join_collapse_limit or from_collapse_limit.
 *
 * NOTE: when dealing with inner joins, it is appropriate to let a qual clause
 * be evaluated at the lowest level where all the variables it mentions are
 * available.  However, we cannot push a qual down into the nullable side(s)
 * of an outer join since the qual might eliminate matching rows and cause a
 * NULL row to be incorrectly emitted by the join.	Therefore, we artificially
 * OR the minimum-relids of such an outer join into the required_relids of
 * clauses appearing above it.	This forces those clauses to be delayed until
 * application of the outer join (or maybe even higher in the join tree).
 */
List* deconstruct_jointree(PlannerInfo* root, Relids* non_keypreserved)
{
    List *result = NIL;
    Relids qualscope = NULL;
    Relids inner_join_rels = NULL;
    List *postponed_qual_list = NIL;
    List* result2 = NIL;

    /* Start recursion at top of jointree */
    AssertEreport(
        root->parse->jointree != NULL && IsA(root->parse->jointree, FromExpr), MOD_OPT, "From expression is required.");

    result = deconstruct_recurse(root, (Node *) root->parse->jointree, false,
                                &qualscope, &inner_join_rels, &postponed_qual_list, non_keypreserved);

    /* Shouldn't be any leftover quals */
    Assert(postponed_qual_list == NIL);

    if (root->parse->commandType == CMD_DELETE ||
    root->parse->commandType == CMD_UPDATE) {
        Bitmapset* checkDuplicate = NULL;
        List* result2 = NIL;
        ListCell* lc = NULL;
        foreach (lc, result) {
            RangeTblRef* rtf = (RangeTblRef*)lfirst(lc);
            if (!bms_is_member(rtf->rtindex, checkDuplicate)) {
                result2 = lappend(result2, rtf);
                checkDuplicate = bms_add_member(checkDuplicate, rtf->rtindex);
            }
        }
        list_free(result);
        bms_free(checkDuplicate);
        result = result2;
    }

    return result;
}

/*
 * process_security_barrier_quals
 *	  Transfer security-barrier quals into relation's baserestrictinfo list.
 *
 * The rewriter put any relevant security-barrier conditions into the RTE's
 * securityQuals field, but it's now time to copy them into the rel's
 * baserestrictinfo.
 *
 * In inheritance cases, we only consider quals attached to the parent rel
 * here; they will be valid for all children too, so it's okay to consider
 * them for purposes like equivalence class creation.  Quals attached to
 * individual child rels will be dealt with during path creation.
 */
static void process_security_barrier_quals(
    PlannerInfo* root, const RangeTblEntry* rte, Relids qualscope, bool below_outer_join)
{
    ListCell* cell1 = NULL;
    ListCell* cell2 = NULL;
    List* quals = NIL;
    Node* qual = NULL;
    Index security_level = 0;

    /*
     * Each element of the securityQuals list has been preprocessed into an
     * implicitly-ANDed list of clauses.
     */
    foreach (cell1, rte->securityQuals) {
        quals = (List*)lfirst(cell1);

        foreach (cell2, quals) {
            qual = (Node*)lfirst(cell2);

            distribute_qual_to_rels(
                root, qual, false, below_outer_join, JOIN_INNER, security_level, qualscope, qualscope, NULL, NULL, NULL, false);
        }

        /*
         * All the clauses in a given sublist have the same security level,
         * but successive sublists get higher levels.
         */
        security_level++;
    }

    /* Assert that qual_security_level is higher than anything we just used */
    Assert(security_level <= root->qualSecurityLevel);
}

#define JATTR_TAB_HASH_SIZE 64

typedef struct JoinAttrEntry {
    Index relidx;
    Bitmapset* attrs;
} JoinAttrEntry;

static bool is_equals_operator(int operid)
{
    bool result = false;
    CatCList* catlist = NULL;
    int i;
    /*
     * Search pg_amop to see if the operid is registered as the "="
     */
    catlist = SearchSysCacheList1(AMOPOPID, ObjectIdGetDatum(operid));
    for (i = 0; i < catlist->n_members; i++) {
        HeapTuple tuple = t_thrd.lsc_cxt.FetchTupleFromCatCList(catlist, i);
        Form_pg_amop aform = (Form_pg_amop)GETSTRUCT(tuple);
        if (aform->amopstrategy == BTEqualStrategyNumber) {
            result = true;
            break;
        }
    }
    ReleaseSysCacheList(catlist);
    return result;

}

static bool rel_is_member_of_non_keypreserved(PlannerInfo* root, Index relidx, Relids non_keypreserved)
{
    Relids tmpset = bms_copy(non_keypreserved);
    int x = 0;
    Oid relid = root->simple_rte_array[relidx]->relid;
    while ((x = bms_first_member(tmpset)) >= 0) {
        if (relid ==  root->simple_rte_array[x]->relid) {
            bms_free_ext(tmpset);
            return true;
        }
    }
    bms_free_ext(tmpset);
    return false;
}

static void find_non_keypreservered_rels(PlannerInfo* root, HTAB* htab, Relids* non_keypreserved,
                                                 JoinType type, RangeTblRef* leftpart, RangeTblRef* rightpart)
{
    HASH_SEQ_STATUS status;
    JoinAttrEntry *entry = NULL;
    hash_seq_init(&status, htab);
    bool left_is_key_preserved = true;
    bool right_is_key_preserved = true;
    while ((entry = (JoinAttrEntry *) hash_seq_search(&status)) != NULL) {
        if (bms_num_members(*non_keypreserved) > 1) {
            ereport(ERROR, (errcode(ERRCODE_DATA_EXCEPTION),
                    errmsg("Cannot sample a join view without a key-preserved table")));
        }
        Index relidx = entry->relidx;
        Oid relid = root->simple_rte_array[relidx]->relid;
        Relids jattrs = entry->attrs;
        Relation relation = relation_open(relid, AccessShareLock);
        Assert(!RelationIsBucket(relation) && !RelationIsPartition(relation));
        /* Fast path if definitely no indexes */
        if (!RelationGetForm(relation)->relhasindex) {
            *non_keypreserved = bms_add_member(*non_keypreserved, relidx);
            relation_close(relation, AccessShareLock);
            continue;
        }
        List* indexoidlist = NIL;
        ListCell* l = NULL;
        Oid relpkindex;
        bool is_key_preserved = false;
        /* Get cached list of index OIDs */
        indexoidlist = RelationGetIndexList(relation);
        /* Fall out if no indexes (but relhasindex was set) */
        if (indexoidlist == NIL) {
            *non_keypreserved = bms_add_member(*non_keypreserved, relidx);
            relation_close(relation, AccessShareLock);
            continue;
        }
        relpkindex = relation->rd_pkindex;
        foreach (l, indexoidlist) {
            Oid indexOid = lfirst_oid(l);
            Relation indexDesc;
            IndexInfo* indexInfo = NULL;
            int i;
            bool isKey = false;    /* candidate key */
            bool isPK;            /* primary key */
            Bitmapset* uindexattrs = NULL;
            Bitmapset* pkindexattrs = NULL;       /* columns in the primary index */
            indexDesc = index_open(indexOid, AccessShareLock);
            /* Extract index key information from the index's pg_index row */
            indexInfo = BuildIndexInfo(indexDesc);
            /* Is this a primary key? */
            isPK = (indexOid == relpkindex);
            /* Can this index be referenced by a foreign key? */
            isKey = indexInfo->ii_Unique && indexInfo->ii_Expressions == NIL && indexInfo->ii_Predicate == NIL;
            if (!isPK && !isKey) {
                index_close(indexDesc, AccessShareLock);
                continue;
            }
            /* Collect simple attribute references */
            for (i = 0; i < indexInfo->ii_NumIndexAttrs; i++) {
               int attrnum = indexInfo->ii_KeyAttrNumbers[i];
               if (attrnum != 0) {
                   if (isKey && i < indexInfo->ii_NumIndexKeyAttrs) {
                       uindexattrs = bms_add_member(uindexattrs, attrnum);
                   }    
                   if (isPK) {
                       pkindexattrs = bms_add_member(pkindexattrs, attrnum);
                   }
               }
            }    
            index_close(indexDesc, AccessShareLock);
            if ((!bms_is_empty(uindexattrs) && bms_is_subset(uindexattrs, jattrs)) ||
                (!bms_is_empty(pkindexattrs) && bms_is_subset(pkindexattrs, jattrs))) { /* the rel is key-preserved*/
                is_key_preserved = true;
                break;
            }
        }
        /* always false if leftpart->rtindex < 0 */
        if (leftpart && !is_key_preserved && leftpart->rtindex >= 0 && relidx == (Index)leftpart->rtindex) {
            left_is_key_preserved = false;
        }
        if (rightpart && !is_key_preserved &&leftpart->rtindex >= 0 && relidx == (Index)rightpart->rtindex) {
            right_is_key_preserved = false;
        }
        if ((!is_key_preserved && rel_is_member_of_non_keypreserved(root, relidx, *non_keypreserved)) ||
            (type == JOIN_LEFT && !right_is_key_preserved) ||
            (type == JOIN_INNER && !right_is_key_preserved && !left_is_key_preserved)) {
            ereport(ERROR, (errcode(ERRCODE_DATA_EXCEPTION),
                    errmsg("Cannot sample a join view without a key-preserved table")));
        }
        if (!is_key_preserved) {
            *non_keypreserved = bms_add_member(*non_keypreserved, (int)relidx);
        }
        relation_close(relation, AccessShareLock);
    }
}

static void handle_join_view_operand(PlannerInfo* root, Var* operand, HTAB* htab, RangeTblRef* rtref)
{
    if (!rtref) {
        return;
    }
    Index varno = ((Var*)operand)->varno;
    AttrNumber varattno = ((Var*)operand)->varattno;
    RangeTblEntry* rte = root->simple_rte_array[varno];
    JoinAttrEntry* attrentry = NULL;
    Bitmapset* attrs;
    Assert(rte->rtekind == RTE_RELATION);
    bool found = false;
    /* Lookup current element in hashtable, adding it if new */
    attrentry = (JoinAttrEntry*)hash_search(htab, &varno, HASH_ENTER, &found);
    if (found) {
        attrs = attrentry->attrs;
        attrs = bms_add_member(attrs, varattno);
    } else {
        attrs = bms_make_singleton(varattno);
        attrentry->attrs = attrs;
    }
}

static void check_join_view_quals(PlannerInfo* root, List* quals, Relids* non_keypreserved,
                             JoinType type, RangeTblRef* leftpart, RangeTblRef* rightpart)
{
    HASHCTL ctl;
    HTAB* htab = NULL;
    errno_t rc = EOK;
    rc = memset_s(&ctl, sizeof(ctl), 0, sizeof(ctl));
    securec_check(rc, "\0", "\0");
    MemoryContext tmp_hash_context = AllocSetContextCreate(CurrentMemoryContext,
                                                           "hashtable temporary context",
                                                           ALLOCSET_DEFAULT_MINSIZE,
                                                           ALLOCSET_DEFAULT_INITSIZE,
                                                           ALLOCSET_DEFAULT_MAXSIZE);
    ctl.keysize = sizeof(Index);
    ctl.entrysize = sizeof(JoinAttrEntry);
    ctl.hash = oid_hash;
    ctl.hcxt = tmp_hash_context;
    htab = hash_create(
        "table's attrs of quals", JATTR_TAB_HASH_SIZE, &ctl, HASH_ELEM | HASH_FUNCTION | HASH_CONTEXT);
    ListCell* l;
    foreach (l, quals) {
        Node* qual = (Node*)lfirst(l);
        Node* left_operand;
        Node* right_operand;
        VariableStatData leftvar;
        VariableStatData rightvar;
        /* If it's a binary opclause, check operator and operand*/
        if (is_opclause(qual) && list_length(((OpExpr*)qual)->args) == 2) {
            Oid opno = ((OpExpr*)qual)->opno;
            left_operand = get_leftop((Expr*)qual);
            right_operand = get_rightop((Expr*)qual);
            examine_variable(root, left_operand, 0, &leftvar);
            examine_variable(root, right_operand, 0, &rightvar);
            if (is_equals_operator(opno)) { /* equal operator */
                if (IsA(leftvar.var, Var) && IsA(rightvar.var, Var)) {
                    handle_join_view_operand(root, (Var*)leftvar.var, htab, leftpart);
                    handle_join_view_operand(root, (Var*)rightvar.var, htab, rightpart);
                } else if (IsA(leftvar.var, Var) && IsA(rightvar.var, Const)) {
                    handle_join_view_operand(root, (Var*)leftvar.var, htab, leftpart);
                } else if (IsA(rightvar.var, Var) && IsA(leftvar.var, Const)) {
                    handle_join_view_operand(root, (Var*)rightvar.var, htab, rightpart);
                } else {
                    ereport(ERROR, (errcode(ERRCODE_DATA_EXCEPTION),
                            errmsg("Cannot sample a join view without a key-preserved table")));
                }
            } 
        }
        ReleaseVariableStats(leftvar);
        ReleaseVariableStats(rightvar);
    }
    /* Check if at most one of the tables associated with the current join is non-key-prereserved */
    find_non_keypreservered_rels(root, htab, non_keypreserved, type, leftpart, rightpart);
    if (bms_num_members(*non_keypreserved) > 1) {
        ereport(ERROR, (errcode(ERRCODE_DATA_EXCEPTION),
                errmsg("Cannot sample a join view without a key-preserved table")));
    }
    /* Done with the hash table. */
    hash_destroy(htab);
}

/*
 * deconstruct_recurse
 *	  One recursion level of deconstruct_jointree processing.
 *
 * Inputs:
 *	jtnode is the jointree node to examine
 *	below_outer_join is TRUE if this node is within the nullable side of a
 *		higher-level outer join
 * Outputs:
 *	*qualscope gets the set of base Relids syntactically included in this
 *		jointree node (do not modify or free this, as it may also be pointed
 *		to by RestrictInfo and SpecialJoinInfo nodes)
 *	*inner_join_rels gets the set of base Relids syntactically included in
 *		inner joins appearing at or below this jointree node (do not modify
 *		or free this, either)
 *	Return value is the appropriate joinlist for this jointree node
 *
 * In addition, entries will be added to root->join_info_list for outer joins.
 */
static List* deconstruct_recurse(PlannerInfo* root, Node* jtnode,
                                bool below_outer_join, Relids* qualscope,
                            Relids* inner_join_rels, List **postponed_qual_list, Relids* non_keypreserved)
{
    List* joinlist = NIL;

    if (jtnode == NULL) {
        *qualscope = NULL;
        *inner_join_rels = NULL;
        return NIL;
    }
    if (IsA(jtnode, RangeTblRef)) {
        int varno = ((RangeTblRef*)jtnode)->rtindex;

        /* No quals to deal with, just return correct result */
        *qualscope = bms_make_singleton(varno);
        /* Deal with any securityQuals attached to the RTE */
        if (root->qualSecurityLevel > 0)
            process_security_barrier_quals(root, root->simple_rte_array[varno], *qualscope, below_outer_join);
        /* A single baserel does not create an inner join */
        *inner_join_rels = NULL;
        joinlist = list_make1(jtnode);
    } else if (IsA(jtnode, FromExpr)) {
        FromExpr* f = (FromExpr*)jtnode;
        List *child_postponed_quals = NIL;
        int remaining;
        ListCell* l = NULL;

        /*
         * First, recurse to handle child joins.  We collapse subproblems into
         * a single joinlist whenever the resulting joinlist wouldn't exceed
         * from_collapse_limit members.  Also, always collapse one-element
         * subproblems, since that won't lengthen the joinlist anyway.
         */
        *qualscope = NULL;
        *inner_join_rels = NULL;
        joinlist = NIL;
        remaining = list_length(f->fromlist);
        foreach (l, f->fromlist) {
            Relids sub_qualscope;
            List* sub_joinlist = NIL;
            int sub_members;

            sub_joinlist = deconstruct_recurse(root, (Node*)lfirst(l), below_outer_join,
                        &sub_qualscope, inner_join_rels, &child_postponed_quals, non_keypreserved);
            *qualscope = bms_add_members(*qualscope, sub_qualscope);
            sub_members = list_length(sub_joinlist);
            remaining--;
            if (sub_members <= 1 ||
                list_length(joinlist) + sub_members + remaining <= u_sess->attr.attr_sql.from_collapse_limit)
                joinlist = list_concat(joinlist, sub_joinlist);
            else
                joinlist = lappend(joinlist, sub_joinlist);
        }

        /*
         * A FROM with more than one list element is an inner join subsuming
         * all below it, so we should report inner_join_rels = qualscope. If
         * there was exactly one element, we should (and already did) report
         * whatever its inner_join_rels were.  If there were no elements (is
         * that possible?) the initialization before the loop fixed it.
         */
        if (list_length(f->fromlist) > 1)
            *inner_join_rels = *qualscope;

        /*
         * Try to process any quals postponed by children.  If they need
         * further postponement, add them to my output postponed_qual_list.
         */
        foreach(l, child_postponed_quals) {
            PostponedQual *pq = (PostponedQual *) lfirst(l);

            if (bms_is_subset(pq->relids, *qualscope))
                distribute_qual_to_rels(root, pq->qual,
                                        false, below_outer_join, JOIN_INNER,
                                        root->qualSecurityLevel,
                                        *qualscope, NULL, NULL, NULL,
                                        NULL, FALSE);
            else
                *postponed_qual_list = lappend(*postponed_qual_list, pq);
        }

        /*
         * Now process the top-level quals.
         */
        foreach (l, (List*)f->quals) {
            Node* qual = (Node*)lfirst(l);
            distribute_qual_to_rels(root, qual, false, below_outer_join, JOIN_INNER,
                root->qualSecurityLevel, *qualscope, NULL, NULL, NULL, postponed_qual_list, FALSE);
        }
    } else if (IsA(jtnode, JoinExpr)) {
        JoinExpr* j = (JoinExpr*)jtnode;
        List* child_postponed_quals = NIL;
        Relids leftids = NULL;
        Relids rightids = NULL;
        Relids left_inners, right_inners, nonnullable_rels, ojscope;
        List* leftjoinlist = NIL;
        List* rightjoinlist = NIL;
        List* my_quals;
        SpecialJoinInfo* sjinfo = NULL;
        ListCell* l = NULL;

        /*
         * Order of operations here is subtle and critical.  First we recurse
         * to handle sub-JOINs.  Their join quals will be placed without
         * regard for whether this level is an outer join, which is correct.
         * Then we place our own join quals, which are restricted by lower
         * outer joins in any case, and are forced to this level if this is an
         * outer join and they mention the outer side.	Finally, if this is an
         * outer join, we create a join_info_list entry for the join.  This
         * will prevent quals above us in the join tree that use those rels
         * from being pushed down below this level.  (It's okay for upper
         * quals to be pushed down to the outer side, however.)
         */
        switch (j->jointype) {
            case JOIN_INNER:
                leftjoinlist = deconstruct_recurse(root, j->larg, below_outer_join,
                                                   &leftids, &left_inners,
                                                   &child_postponed_quals, non_keypreserved);
                rightjoinlist = deconstruct_recurse(root, j->rarg, below_outer_join,
                                                   &rightids, &right_inners,
                                                   &child_postponed_quals, non_keypreserved);
                *qualscope = bms_union(leftids, rightids);
                *inner_join_rels = *qualscope;
                /* Inner join adds no restrictions for quals */
                nonnullable_rels = NULL;
                break;
            case JOIN_LEFT:
            case JOIN_ANTI:
            case JOIN_LEFT_ANTI_FULL:
                leftjoinlist = deconstruct_recurse(root, j->larg, below_outer_join,
                                                   &leftids, &left_inners,
                                                   &child_postponed_quals, non_keypreserved);
                rightjoinlist = deconstruct_recurse(root, j->rarg, true,
                                                   &rightids, &right_inners,
                                                   &child_postponed_quals, non_keypreserved);
                *qualscope = bms_union(leftids, rightids);
                *inner_join_rels = bms_union(left_inners, right_inners);
                nonnullable_rels = leftids;
                break;
            case JOIN_SEMI:
                leftjoinlist = deconstruct_recurse(root, j->larg, below_outer_join,
                                                   &leftids, &left_inners,
                                                   &child_postponed_quals, non_keypreserved);
                rightjoinlist = deconstruct_recurse(root, j->rarg, below_outer_join,
                                                   &rightids, &right_inners,
                                                   &child_postponed_quals, non_keypreserved);
                *qualscope = bms_union(leftids, rightids);
                *inner_join_rels = bms_union(left_inners, right_inners);
                /* Semi join adds no restrictions for quals */
                nonnullable_rels = NULL;
                break;
            case JOIN_FULL:
                leftjoinlist = deconstruct_recurse(root, j->larg, true,
                                                   &leftids, &left_inners,
                                                   &child_postponed_quals, non_keypreserved);
                rightjoinlist = deconstruct_recurse(root, j->rarg, true,
                                                   &rightids, &right_inners,
                                                   &child_postponed_quals, non_keypreserved);
                *qualscope = bms_union(leftids, rightids);
                *inner_join_rels = bms_union(left_inners, right_inners);
                /* each side is both outer and inner */
                nonnullable_rels = *qualscope;
                break;
            default: {
                /* JOIN_RIGHT was eliminated during reduce_outer_joins() */
                ereport(ERROR,
                    (errmodule(MOD_OPT),
                        errcode(ERRCODE_UNRECOGNIZED_NODE_TYPE),
                        errmsg("unrecognized join type in one level processing of deconstruct jointree: %d",
                            (int)j->jointype)));

                nonnullable_rels = NULL; /* keep compiler quiet */
                leftjoinlist = rightjoinlist = NIL;
            } break;
        }
        if (root->simple_rel_array[1] == NULL && root->simple_rte_array[1]->tablesample != NULL) {
            Node* leftpart = (list_length(leftjoinlist) == 1) ? (Node*)linitial(leftjoinlist) : NULL;
            Node* rightpart = (list_length(rightjoinlist) == 1) ? (Node*)linitial(rightjoinlist) : NULL;
            check_join_view_quals(root, (List*)j->quals, non_keypreserved, j->jointype, (RangeTblRef*)leftpart, (RangeTblRef*)rightpart);
        }

        /*
         * Try to process any quals postponed by children.  If they need
         * further postponement, add them to my output postponed_qual_list.
         * Quals that can be processed now must be included in my_quals, so
         * that they'll be handled properly in make_outerjoininfo.
         */
        my_quals = NIL;
        foreach(l, child_postponed_quals) {
            PostponedQual *pq = (PostponedQual *) lfirst(l);
            
            if (bms_is_subset(pq->relids, *qualscope)) {
                my_quals = lappend(my_quals, pq->qual);
            } else {
                /*
                 * We should not be postponing any quals past an outer join.
                 * If this Assert fires, pull_up_subqueries() messed up.
                 */
                Assert(j->jointype == JOIN_INNER);
                *postponed_qual_list = lappend(*postponed_qual_list, pq);
            }
        }
        my_quals = list_concat(my_quals, (List *) j->quals);

        /*
         * For an OJ, form the SpecialJoinInfo now, because we need the OJ's
         * semantic scope (ojscope) to pass to distribute_qual_to_rels.  But
         * we mustn't add it to join_info_list just yet, because we don't want
         * distribute_qual_to_rels to think it is an outer join below us.
         *
         * Semijoins are a bit of a hybrid: we build a SpecialJoinInfo, but we
         * want ojscope = NULL for distribute_qual_to_rels.
         */
        if (j->jointype != JOIN_INNER) {
            sjinfo = make_outerjoininfo(root, leftids, rightids, *inner_join_rels,
                                        j->jointype, my_quals);
            if (j->jointype == JOIN_SEMI)
                ojscope = NULL;
            else
                ojscope = bms_union(sjinfo->min_lefthand, sjinfo->min_righthand);
        } else {
            sjinfo = NULL;
            ojscope = NULL;
        }

        /* Process the JOIN's qual clauses */
        foreach (l, my_quals) {
            Node* qual = (Node*)lfirst(l);

            distribute_qual_to_rels(root,
                qual,
                false,
                below_outer_join,
                j->jointype,
                root->qualSecurityLevel,
                *qualscope,
                ojscope,
                nonnullable_rels,
                NULL,
                postponed_qual_list,
                j->isAsof);
        }

        /* Now we can add the SpecialJoinInfo to join_info_list */
        if (sjinfo != NULL) {
            root->join_info_list = lappend(root->join_info_list, sjinfo);
            /* Each time we do that, recheck placeholder eval levels */
            update_placeholder_eval_levels(root, sjinfo);
        }

        /*
         * Finally, compute the output joinlist.  We fold subproblems together
         * except at a FULL JOIN or where join_collapse_limit would be
         * exceeded.
         */
        if (j->jointype == JOIN_FULL) {
            /* force the join order exactly at this node */
            joinlist = list_make1(list_make2(leftjoinlist, rightjoinlist));
        } else if (list_length(leftjoinlist) + list_length(rightjoinlist) <=
                   u_sess->attr.attr_sql.join_collapse_limit) {
            /* OK to combine subproblems */
            joinlist = list_concat(leftjoinlist, rightjoinlist);
        } else {
            /* can't combine, but needn't force join order above here */
            Node* leftpart = NULL;
            Node* rightpart = NULL;

            /* avoid creating useless 1-element sublists */
            if (list_length(leftjoinlist) == 1)
                leftpart = (Node*)linitial(leftjoinlist);
            else
                leftpart = (Node*)leftjoinlist;
            if (list_length(rightjoinlist) == 1)
                rightpart = (Node*)linitial(rightjoinlist);
            else
                rightpart = (Node*)rightjoinlist;
            joinlist = list_make2(leftpart, rightpart);
        }
    } else {
        ereport(ERROR,
            (errmodule(MOD_OPT),
                errcode(ERRCODE_UNRECOGNIZED_NODE_TYPE),
                errmsg("unrecognized node type in one level of deconstruct jointree: %d", (int)nodeTag(jtnode))));
        joinlist = NIL; /* keep compiler quiet */
    }
    return joinlist;
}

void process_security_clause_appendrel(PlannerInfo *root)
{
    if (root->qualSecurityLevel == 0) {
        return;
    }
    ListCell* lc = NULL;
    foreach(lc, root->append_rel_list) {
        AppendRelInfo* appinfo = (AppendRelInfo*)lfirst(lc);
        Index childRTindex = appinfo->child_relid;
        Relids qualscope = bms_make_singleton((int)childRTindex);
        RangeTblEntry* childRTE = root->simple_rte_array[childRTindex];
        process_security_barrier_quals(root, childRTE, qualscope, false);
        pfree(qualscope);
    }
}

/*
 * make_outerjoininfo
 *	  Build a SpecialJoinInfo for the current outer join
 *
 * Inputs:
 *	left_rels: the base Relids syntactically on outer side of join
 *	right_rels: the base Relids syntactically on inner side of join
 *	inner_join_rels: base Relids participating in inner joins below this one
 *	jointype: what it says (must always be LEFT, FULL, SEMI, or ANTI)
 *	clause: the outer join's join condition (in implicit-AND format)
 *
 * The node should eventually be appended to root->join_info_list, but we
 * do not do that here.
 *
 * Note: we assume that this function is invoked bottom-up, so that
 * root->join_info_list already contains entries for all outer joins that are
 * syntactically below this one.
 */
static SpecialJoinInfo* make_outerjoininfo(
    PlannerInfo* root, Relids left_rels, Relids right_rels, Relids inner_join_rels, JoinType jointype, List* clause)
{
    SpecialJoinInfo* sjinfo = makeNode(SpecialJoinInfo);
    Relids clause_relids;
    Relids strict_relids;
    Relids min_lefthand;
    Relids min_righthand;
    ListCell* l = NULL;

    /*
     * We should not see RIGHT JOIN here because left/right were switched
     * earlier
     */
    AssertEreport(jointype != JOIN_RIGHT && jointype != JOIN_INNER && jointype != JOIN_RIGHT_ANTI_FULL,
        MOD_OPT,
        "unexpected join type.");

    /*
     * Presently the executor cannot support FOR [KEY] UPDATE/SHARE marking of rels
     * appearing on the nullable side of an outer join. (It's somewhat unclear
     * what that would mean, anyway: what should we mark when a result row is
     * generated from no element of the nullable relation?)  So, complain if
     * any nullable rel is FOR [KEY] UPDATE/SHARE.
     *
     * You might be wondering why this test isn't made far upstream in the
     * parser.	It's because the parser hasn't got enough info --- consider
     * FOR UPDATE applied to a view.  Only after rewriting and flattening do
     * we know whether the view contains an outer join.
     *
     * We use the original RowMarkClause list here; the PlanRowMark list would
     * list everything.
     */
    foreach (l, root->parse->rowMarks) {
        RowMarkClause* rc = (RowMarkClause*)lfirst(l);

        if (bms_is_member(rc->rti, right_rels) || (jointype == JOIN_FULL && bms_is_member(rc->rti, left_rels))) {
            ereport(ERROR,
                (errmodule(MOD_OPT),
                    errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
#ifndef ENABLE_MULTIPLE_NODES
                    errmsg("SELECT FOR UPDATE/SHARE/NO KEY UPDATE/KEY SHARE cannot be applied to the nullable side "
                           "of an outer join")));
#else
                    errmsg("SELECT FOR UPDATE/SHARE cannot be applied to the nullable side of an outer join")));
#endif
        }
    }

    sjinfo->syn_lefthand = left_rels;
    sjinfo->syn_righthand = right_rels;
    sjinfo->jointype = jointype;
    /* this always starts out false */
    sjinfo->delay_upper_joins = false;
    sjinfo->join_quals = clause;

    /* If it's a full join, no need to be very smart */
    if (jointype == JOIN_FULL) {
        sjinfo->min_lefthand = bms_copy(left_rels);
        sjinfo->min_righthand = bms_copy(right_rels);
        sjinfo->lhs_strict = false; /* don't care about this */
        return sjinfo;
    }

    /*
     * Retrieve all relids mentioned within the join clause.
     */
    clause_relids = pull_varnos((Node*)clause);

    /*
     * For which relids is the clause strict, ie, it cannot succeed if the
     * rel's columns are all NULL?
     */
    strict_relids = find_nonnullable_rels((Node*)clause);

    /* Remember whether the clause is strict for any LHS relations */
    sjinfo->lhs_strict = bms_overlap(strict_relids, left_rels);

    /*
     * Required LHS always includes the LHS rels mentioned in the clause. We
     * may have to add more rels based on lower outer joins; see below.
     */
    min_lefthand = bms_intersect(clause_relids, left_rels);

    /*
     * Similarly for required RHS.	But here, we must also include any lower
     * inner joins, to ensure we don't try to commute with any of them.
     */
    min_righthand = bms_int_members(bms_union(clause_relids, inner_join_rels), right_rels);

    /*
     * Now check previous outer joins for ordering restrictions.
     */
    foreach (l, root->join_info_list) {
        SpecialJoinInfo* otherinfo = (SpecialJoinInfo*)lfirst(l);

        /*
         * A full join is an optimization barrier: we can't associate into or
         * out of it.  Hence, if it overlaps either LHS or RHS of the current
         * rel, expand that side's min relset to cover the whole full join.
         */
        if (otherinfo->jointype == JOIN_FULL) {
            if (bms_overlap(left_rels, otherinfo->syn_lefthand) || bms_overlap(left_rels, otherinfo->syn_righthand)) {
                min_lefthand = bms_add_members(min_lefthand, otherinfo->syn_lefthand);
                min_lefthand = bms_add_members(min_lefthand, otherinfo->syn_righthand);
            }
            if (bms_overlap(right_rels, otherinfo->syn_lefthand) || bms_overlap(right_rels, otherinfo->syn_righthand)) {
                min_righthand = bms_add_members(min_righthand, otherinfo->syn_lefthand);
                min_righthand = bms_add_members(min_righthand, otherinfo->syn_righthand);
            }
            /* Needn't do anything else with the full join */
            continue;
        }

        /*
         * For a lower OJ in our LHS, if our join condition uses the lower
         * join's RHS and is not strict for that rel, we must preserve the
         * ordering of the two OJs, so add lower OJ's full syntactic relset to
         * min_lefthand.  (We must use its full syntactic relset, not just its
         * min_lefthand + min_righthand.  This is because there might be other
         * OJs below this one that this one can commute with, but we cannot
         * commute with them if we don't with this one.)  Also, if the current
         * join is a semijoin or antijoin, we must preserve ordering
         * regardless of strictness.
         *
         * Note: I believe we have to insist on being strict for at least one
         * rel in the lower OJ's min_righthand, not its whole syn_righthand.
         */
        if (bms_overlap(left_rels, otherinfo->syn_righthand)) {
            if (bms_overlap(clause_relids, otherinfo->syn_righthand) &&
                (jointype == JOIN_SEMI || jointype == JOIN_ANTI ||
                    !bms_overlap(strict_relids, otherinfo->min_righthand))) {
                min_lefthand = bms_add_members(min_lefthand, otherinfo->syn_lefthand);
                min_lefthand = bms_add_members(min_lefthand, otherinfo->syn_righthand);
            }
        }

        /*
         * For a lower OJ in our RHS, if our join condition does not use the
         * lower join's RHS and the lower OJ's join condition is strict, we
         * can interchange the ordering of the two OJs; otherwise we must add
         * the lower OJ's full syntactic relset to min_righthand.
         *
         * Also, if our join condition does not use the lower join's LHS
         * either, force the ordering to be preserved.  Otherwise we can end
         * up with SpecialJoinInfos with identical min_righthands, which can
         * confuse join_is_legal (see discussion in backend/optimizer/README).
         *
         * Also, we must preserve ordering anyway if either the current join
         * or the lower OJ is either a semijoin or an antijoin.
         *
         * Here, we have to consider that "our join condition" includes any
         * clauses that syntactically appeared above the lower OJ and below
         * ours; those are equivalent to degenerate clauses in our OJ and must
         * be treated as such.	Such clauses obviously can't reference our
         * LHS, and they must be non-strict for the lower OJ's RHS (else
         * reduce_outer_joins would have reduced the lower OJ to a plain
         * join).  Hence the other ways in which we handle clauses within our
         * join condition are not affected by them.  The net effect is
         * therefore sufficiently represented by the delay_upper_joins flag
         * saved for us by check_outerjoin_delay.
         */
        if (bms_overlap(right_rels, otherinfo->syn_righthand)) {
            if (bms_overlap(clause_relids, otherinfo->syn_righthand) ||
                !bms_overlap(clause_relids, otherinfo->min_lefthand) || jointype == JOIN_SEMI ||
                jointype == JOIN_ANTI || otherinfo->jointype == JOIN_SEMI || otherinfo->jointype == JOIN_ANTI ||
                !otherinfo->lhs_strict || otherinfo->delay_upper_joins) {
                min_righthand = bms_add_members(min_righthand, otherinfo->syn_lefthand);
                min_righthand = bms_add_members(min_righthand, otherinfo->syn_righthand);
            }
        }
    }

    /*
     * Examine PlaceHolderVars.  If a PHV is supposed to be evaluated within
     * this join's nullable side, and it may get used above this join, then
     * ensure that min_righthand contains the full eval_at set of the PHV.
     * This ensures that the PHV actually can be evaluated within the RHS.
     * Note that this works only because we should already have determined the
     * final eval_at level for any PHV syntactically within this join.
     */
    foreach (l, root->placeholder_list) {
        PlaceHolderInfo* phinfo = (PlaceHolderInfo*)lfirst(l);
        Relids ph_syn_level = phinfo->ph_var->phrels;

        /* Ignore placeholder if it didn't syntactically come from RHS */
        if (!bms_is_subset(ph_syn_level, right_rels))
            continue;

        /* Else, prevent join from being formed before we eval the PHV */
        min_righthand = bms_add_members(min_righthand, phinfo->ph_eval_at);
    }

    /*
     * If we found nothing to put in min_lefthand, punt and make it the full
     * LHS, to avoid having an empty min_lefthand which will confuse later
     * processing. (We don't try to be smart about such cases, just correct.)
     * Likewise for min_righthand.
     */
    if (bms_is_empty(min_lefthand))
        min_lefthand = bms_copy(left_rels);
    if (bms_is_empty(min_righthand))
        min_righthand = bms_copy(right_rels);

    /* Now they'd better be nonempty */
    AssertEreport(!bms_is_empty(min_lefthand) && !bms_is_empty(min_righthand), MOD_OPT, "bms should not be null");
    /* Shouldn't overlap either */
    AssertEreport(!bms_overlap(min_lefthand, min_righthand), MOD_OPT, "bms shouldn't overlap");

    sjinfo->min_lefthand = min_lefthand;
    sjinfo->min_righthand = min_righthand;

    return sjinfo;
}

/*****************************************************************************
 *
 *	  QUALIFICATIONS
 *
 *****************************************************************************/
/*
 * distribute_qual_to_rels
 *	  Add clause information to either the baserestrictinfo or joininfo list
 *	  (depending on whether the clause is a join) of each base relation
 *	  mentioned in the clause.	A RestrictInfo node is created and added to
 *	  the appropriate list for each rel.  Alternatively, if the clause uses a
 *	  mergejoinable operator and is not delayed by outer-join rules, enter
 *	  the left- and right-side expressions into the query's list of
 *	  EquivalenceClasses.
 *
 * 'clause': the qual clause to be distributed
 * 'is_deduced': TRUE if the qual came from implied-equality deduction
 * 'below_outer_join': TRUE if the qual is from a JOIN/ON that is below the
 *		nullable side of a higher-level outer join
 * 'jointype': type of join the qual is from (JOIN_INNER for a WHERE clause)
 * 'security_level': security_level to assign to the qual
 * 'qualscope': set of baserels the qual's syntactic scope covers
 * 'ojscope': NULL if not an outer-join qual, else the minimum set of baserels
 *		needed to form this join
 * 'outerjoin_nonnullable': NULL if not an outer-join qual, else the set of
 *		baserels appearing on the outer (nonnullable) side of the join
 *		(for FULL JOIN this includes both sides of the join, and must in fact
 *		equal qualscope)
 * 'deduced_nullable_relids': if is_deduced is TRUE, the nullable relids to
 *		impute to the clause; otherwise NULL
 *
 * 'qualscope' identifies what level of JOIN the qual came from syntactically.
 * 'ojscope' is needed if we decide to force the qual up to the outer-join
 * level, which will be ojscope not necessarily qualscope.
 *
 * In normal use (when is_deduced is FALSE), at the time this is called,
 * root->join_info_list must contain entries for all and only those special
 * joins that are syntactically below this qual.  But when is_deduced is TRUE,
 * we are adding new deduced clauses after completion of deconstruct_jointree,
 * so it cannot be assumed that root->join_info_list has anything to do with
 * qual placement.
 */
void distribute_qual_to_rels(PlannerInfo* root, Node* clause, bool is_deduced, bool below_outer_join, JoinType jointype,
    Index security_level, Relids qualscope, Relids ojscope, Relids outerjoin_nonnullable,
    Relids deduced_nullable_relids, List **postponed_qual_list, bool is_asof)
{
    Relids relids;
    bool is_pushed_down = false;
    bool outerjoin_delayed = false;
    bool pseudoconstant = false;
    bool maybe_equivalence = false;
    bool maybe_outer_join = false;
    Relids nullable_relids;
    RestrictInfo* restrictinfo = NULL;

    /*
     * Retrieve all relids mentioned within the clause.
     */
    relids = pull_varnos(clause);

    /*
     * In ordinary SQL, a WHERE or JOIN/ON clause can't reference any rels
     * that aren't within its syntactic scope; however, if we pulled up a
     * LATERAL subquery then we might find such references in quals that have
     * been pulled up.  We need to treat such quals as belonging to the join
     * level that includes every rel they reference.  Although we could make
     * pull_up_subqueries() place such quals correctly to begin with, it's
     * easier to handle it here.  When we find a clause that contains Vars
     * outside its syntactic scope, we add it to the postponed-quals list, and
     * process it once we've recursed back up to the appropriate join level.
     */
    if (!bms_is_subset(relids, qualscope))
    {
        PostponedQual *pq = (PostponedQual *) palloc(sizeof(PostponedQual));
    
        Assert(root->hasLateralRTEs);   /* shouldn't happen otherwise */
        Assert(jointype == JOIN_INNER); /* mustn't postpone past outer join */
        Assert(!is_deduced);    /* shouldn't be deduced, either */
        pq->qual = clause;
        pq->relids = relids;
        *postponed_qual_list = lappend(*postponed_qual_list, pq);
        return;
    }

    /*
     * If it's an outer-join clause, also check that relids is a subset of
     * ojscope. (This should not fail if the syntactic scope check passed.)
     */
    if (ojscope && !bms_is_subset(relids, ojscope))
        ereport(ERROR,
            (errmodule(MOD_OPT),
                errcode(ERRCODE_OPTIMIZER_INCONSISTENT_STATE),
                (errmsg("JOIN qualification cannot refer to other relations"))));

    /*
     * If the clause is variable-free, our normal heuristic for pushing it
     * down to just the mentioned rels doesn't work, because there are none.
     *
     * If the clause is an outer-join clause, we must force it to the OJ's
     * semantic level to preserve semantics.
     *
     * Otherwise, when the clause contains volatile functions, we force it to
     * be evaluated at its original syntactic level.  This preserves the
     * expected semantics.
     *
     * When the clause contains no volatile functions either, it is actually a
     * pseudoconstant clause that will not change value during any one
     * execution of the plan, and hence can be used as a one-time qual in a
     * gating Result plan node.  We put such a clause into the regular
     * RestrictInfo lists for the moment, but eventually createplan.c will
     * pull it out and make a gating Result node immediately above whatever
     * plan node the pseudoconstant clause is assigned to.	It's usually best
     * to put a gating node as high in the plan tree as possible. If we are
     * not below an outer join, we can actually push the pseudoconstant qual
     * all the way to the top of the tree.	If we are below an outer join, we
     * leave the qual at its original syntactic level (we could push it up to
     * just below the outer join, but that seems more complex than it's
     * worth).
     */
    if (bms_is_empty(relids)) {
        if (ojscope) {
            /* clause is attached to outer join, eval it there */
            relids = bms_copy(ojscope);
            /* mustn't use as gating qual, so don't mark pseudoconstant */
        } else {
            /* eval at original syntactic level */
            relids = bms_copy(qualscope);
            if (!contain_volatile_functions(clause)) {
                /* mark as gating qual */
                pseudoconstant = true;
                /* tell createplan.c to check for gating quals */
                root->hasPseudoConstantQuals = true;
                /* if not below outer join, push it to top of tree */
                if (!below_outer_join) {
                    relids = get_relids_in_jointree((Node*)root->parse->jointree, false);
                    qualscope = bms_copy(relids);
                }
            }
        }
    }

    /* ----------
     * Check to see if clause application must be delayed by outer-join
     * considerations.
     *
     * A word about is_pushed_down: we mark the qual as "pushed down" if
     * it is (potentially) applicable at a level different from its original
     * syntactic level.  This flag is used to distinguish OUTER JOIN ON quals
     * from other quals pushed down to the same joinrel.  The rules are:
     *		WHERE quals and INNER JOIN quals: is_pushed_down = true.
     *		Non-degenerate OUTER JOIN quals: is_pushed_down = false.
     *		Degenerate OUTER JOIN quals: is_pushed_down = true.
     * A "degenerate" OUTER JOIN qual is one that doesn't mention the
     * non-nullable side, and hence can be pushed down into the nullable side
     * without changing the join result.  It is correct to treat it as a
     * regular filter condition at the level where it is evaluated.
     *
     * Note: it is not immediately obvious that a simple boolean is enough
     * for this: if for some reason we were to attach a degenerate qual to
     * its original join level, it would need to be treated as an outer join
     * qual there.	However, this cannot happen, because all the rels the
     * clause mentions must be in the outer join's min_righthand, therefore
     * the join it needs must be formed before the outer join; and we always
     * attach quals to the lowest level where they can be evaluated.  But
     * if we were ever to re-introduce a mechanism for delaying evaluation
     * of "expensive" quals, this area would need work.
     * ----------
     */
    if (is_deduced) {
        /*
         * If the qual came from implied-equality deduction, it should not be
         * outerjoin-delayed, else deducer blew it.  But we can't check this
         * because the join_info_list may now contain OJs above where the qual
         * belongs.  For the same reason, we must rely on caller to supply the
         * correct nullable_relids set.
         */
        Assert(ojscope == NULL);
        is_pushed_down = true;
        outerjoin_delayed = false;
        nullable_relids = deduced_nullable_relids;
        /* Don't feed it back for more deductions */
        maybe_equivalence = false;
        maybe_outer_join = false;
    } else if (bms_overlap(relids, outerjoin_nonnullable)) {
        /*
         * The qual is attached to an outer join and mentions (some of the)
         * rels on the nonnullable side, so it's not degenerate.
         *
         * We can't use such a clause to deduce equivalence (the left and
         * right sides might be unequal above the join because one of them has
         * gone to NULL) ... but we might be able to use it for more limited
         * deductions, if it is mergejoinable.	So consider adding it to the
         * lists of set-aside outer-join clauses.
         */
        is_pushed_down = false;
        maybe_equivalence = false;
        maybe_outer_join = true;

        /* Check to see if must be delayed by lower outer join */
        outerjoin_delayed = check_outerjoin_delay(root, &relids, &nullable_relids, false);

        /*
         * Now force the qual to be evaluated exactly at the level of joining
         * corresponding to the outer join.  We cannot let it get pushed down
         * into the nonnullable side, since then we'd produce no output rows,
         * rather than the intended single null-extended row, for any
         * nonnullable-side rows failing the qual.
         *
         * (Do this step after calling check_outerjoin_delay, because that
         * trashes relids.)
         */
        Assert(ojscope != NULL);
        relids = ojscope;
        Assert(pseudoconstant == false);
    } else {
        /*
         * Normal qual clause or degenerate outer-join clause.	Either way, we
         * can mark it as pushed-down.
         */
        is_pushed_down = true;

        /* Check to see if must be delayed by lower outer join */
        outerjoin_delayed = check_outerjoin_delay(root, &relids, &nullable_relids, true);

        if (outerjoin_delayed) {
            /* Should still be a subset of current scope ... */
            Assert(root->hasLateralRTEs || bms_is_subset(relids, qualscope));
            Assert(ojscope == NULL || bms_is_subset(relids, ojscope));

            /*
             * Because application of the qual will be delayed by outer join,
             * we mustn't assume its vars are equal everywhere.
             */
            maybe_equivalence = false;

            /*
             * It's possible that this is an IS NULL clause that's redundant
             * with a lower antijoin; if so we can just discard it.  We need
             * not test in any of the other cases, because this will only be
             * possible for pushed-down, delayed clauses.
             */
            if (check_redundant_nullability_qual(root, clause))
                return;
        } else {
            /*
             * Qual is not delayed by any lower outer-join restriction, so we
             * can consider feeding it to the equivalence machinery. However,
             * if it's itself within an outer-join clause, treat it as though
             * it appeared below that outer join (note that we can only get
             * here when the clause references only nullable-side rels).
             */
            maybe_equivalence = true;
            if (outerjoin_nonnullable != NULL)
                below_outer_join = true;
        }

        /*
         * Since it doesn't mention the LHS, it's certainly not useful as a
         * set-aside OJ clause, even if it's in an OJ.
         */
        maybe_outer_join = false;
    }

    /*
     * Build the RestrictInfo node itself.
     */
    restrictinfo = make_restrictinfo((Expr*)clause,
        is_pushed_down,
        outerjoin_delayed,
        pseudoconstant,
        security_level,
        relids,
        outerjoin_nonnullable,
        nullable_relids,
        is_asof);
    /*
     * If it's a join clause (either naturally, or because delayed by
     * outer-join rules), add vars used in the clause to targetlists of their
     * relations, so that they will be emitted by the plan nodes that scan
     * those relations (else they won't be available at the join node!).
     *
     * Note: if the clause gets absorbed into an EquivalenceClass then this
     * may be unnecessary, but for now we have to do it to cover the case
     * where the EC becomes ec_broken and we end up reinserting the original
     * clauses into the plan.
     */
    if (bms_membership(relids) == BMS_MULTIPLE || (IS_STREAM_PLAN && check_param_clause((Node*)restrictinfo->clause))) {
        List* vars = pull_var_clause(clause, PVC_RECURSE_AGGREGATES, PVC_INCLUDE_PLACEHOLDERS);

        add_vars_to_targetlist(root, vars, relids, false);
        list_free_ext(vars);
    }

    /*
     * We check "mergejoinability" of every clause, not only join clauses,
     * because we want to know about equivalences between vars of the same
     * relation, or between vars and consts.
     */
    check_mergejoinable(restrictinfo);

    /*
     * If it is a true equivalence clause, send it to the EquivalenceClass
     * machinery.  We do *not* attach it directly to any restriction or join
     * lists.  The EC code will propagate it to the appropriate places later.
     *
     * If the clause has a mergejoinable operator and is not
     * outerjoin-delayed, yet isn't an equivalence because it is an outer-join
     * clause, the EC code may yet be able to do something with it.  We add it
     * to appropriate lists for further consideration later.  Specifically:
     *
     * If it is a left or right outer-join qualification that relates the two
     * sides of the outer join (no funny business like leftvar1 = leftvar2 +
     * rightvar), we add it to root->left_join_clauses or
     * root->right_join_clauses according to which side the nonnullable
     * variable appears on.
     *
     * If it is a full outer-join qualification, we add it to
     * root->full_join_clauses.  (Ideally we'd discard cases that aren't
     * leftvar = rightvar, as we do for left/right joins, but this routine
     * doesn't have the info needed to do that; and the current usage of the
     * full_join_clauses list doesn't require that, so it's not currently
     * worth complicating this routine's API to make it possible.)
     *
     * If none of the above hold, pass it off to 
     * distribute_restrictinfo_to_rels.
     *
     * In all cases, it's important to initialize the left_ec and right_ec
     * fields of a mergejoinable clause, so that all possibly mergejoinable
     * expressions have representations in EquivalenceClasses.	If
     * process_equivalence is successful, it will take care of that;
     * otherwise, we have to call initialize_mergeclause_eclasses to do it.
     */
    if (restrictinfo->mergeopfamilies) {
        if (maybe_equivalence) {
            if (check_equivalence_delay(root, restrictinfo) &&
                process_equivalence(root, restrictinfo, below_outer_join))
                return;
            /* EC rejected it, so set left_ec/right_ec the hard way ... */
            initialize_mergeclause_eclasses(root, restrictinfo);
            /* ... and fall through to distribute_restrictinfo_to_rels */
        } else if (maybe_outer_join && restrictinfo->can_join) {
            /* we need to set up left_ec/right_ec the hard way */
            initialize_mergeclause_eclasses(root, restrictinfo);
            /* now see if it should go to any outer-join lists */
            if (bms_is_subset(restrictinfo->left_relids, outerjoin_nonnullable) &&
                !bms_overlap(restrictinfo->right_relids, outerjoin_nonnullable)) {
                /* we have outervar = innervar */
                root->left_join_clauses = lappend(root->left_join_clauses, restrictinfo);
                return;
            }
            if (bms_is_subset(restrictinfo->right_relids, outerjoin_nonnullable) &&
                !bms_overlap(restrictinfo->left_relids, outerjoin_nonnullable)) {
                /* we have innervar = outervar */
                root->right_join_clauses = lappend(root->right_join_clauses, restrictinfo);
                return;
            }
            if (jointype == JOIN_FULL) {
                /* FULL JOIN (above tests cannot match in this case) */
                root->full_join_clauses = lappend(root->full_join_clauses, restrictinfo);
                return;
            }
            /* nope, so fall through to distribute_restrictinfo_to_rels */
        } else {
            /* we still need to set up left_ec/right_ec */
            initialize_mergeclause_eclasses(root, restrictinfo);
        }
    }

    /* No EC special case applies, so push it into the clause lists */
    distribute_restrictinfo_to_rels(root, restrictinfo);
}

/*
 * check_outerjoin_delay
 *		Detect whether a qual referencing the given relids must be delayed
 *		in application due to the presence of a lower outer join, and/or
 *		may force extra delay of higher-level outer joins.
 *
 * If the qual must be delayed, add relids to *relids_p to reflect the lowest
 * safe level for evaluating the qual, and return TRUE.  Any extra delay for
 * higher-level joins is reflected by setting delay_upper_joins to TRUE in
 * SpecialJoinInfo structs.  We also compute nullable_relids, the set of
 * referenced relids that are nullable by lower outer joins (note that this
 * can be nonempty even for a non-delayed qual).
 *
 * For an is_pushed_down qual, we can evaluate the qual as soon as (1) we have
 * all the rels it mentions, and (2) we are at or above any outer joins that
 * can null any of these rels and are below the syntactic location of the
 * given qual.	We must enforce (2) because pushing down such a clause below
 * the OJ might cause the OJ to emit null-extended rows that should not have
 * been formed, or that should have been rejected by the clause.  (This is
 * only an issue for non-strict quals, since if we can prove a qual mentioning
 * only nullable rels is strict, we'd have reduced the outer join to an inner
 * join in reduce_outer_joins().)
 *
 * To enforce (2), scan the join_info_list and merge the required-relid sets of
 * any such OJs into the clause's own reference list.  At the time we are
 * called, the join_info_list contains only outer joins below this qual.  We
 * have to repeat the scan until no new relids get added; this ensures that
 * the qual is suitably delayed regardless of the order in which OJs get
 * executed.  As an example, if we have one OJ with LHS=A, RHS=B, and one with
 * LHS=B, RHS=C, it is implied that these can be done in either order; if the
 * B/C join is done first then the join to A can null C, so a qual actually
 * mentioning only C cannot be applied below the join to A.
 *
 * For a non-pushed-down qual, this isn't going to determine where we place the
 * qual, but we need to determine outerjoin_delayed and nullable_relids anyway
 * for use later in the planning process.
 *
 * Lastly, a pushed-down qual that references the nullable side of any current
 * join_info_list member and has to be evaluated above that OJ (because its
 * required relids overlap the LHS too) causes that OJ's delay_upper_joins
 * flag to be set TRUE.  This will prevent any higher-level OJs from
 * being interchanged with that OJ, which would result in not having any
 * correct place to evaluate the qual.	(The case we care about here is a
 * sub-select WHERE clause within the RHS of some outer join.  The WHERE
 * clause must effectively be treated as a degenerate clause of that outer
 * join's condition.  Rather than trying to match such clauses with joins
 * directly, we set delay_upper_joins here, and when the upper outer join
 * is processed by make_outerjoininfo, it will refrain from allowing the
 * two OJs to commute.)
 */
static bool check_outerjoin_delay(PlannerInfo* root, Relids* relids_p, /* in/out parameter */
    Relids* nullable_relids_p,                                         /* output parameter */
    bool is_pushed_down)
{
    Relids relids;
    Relids nullable_relids;
    bool outerjoin_delayed = false;
    bool found_some = false;

    /* fast path if no special joins */
    if (root->join_info_list == NIL) {
        *nullable_relids_p = NULL;
        return false;
    }

    /* must copy relids because we need the original value at the end */
    relids = bms_copy(*relids_p);
    nullable_relids = NULL;
    outerjoin_delayed = false;
    do {
        ListCell* l = NULL;

        found_some = false;
        foreach (l, root->join_info_list) {
            SpecialJoinInfo* sjinfo = (SpecialJoinInfo*)lfirst(l);

            /* do we reference any nullable rels of this OJ? */
            if (bms_overlap(relids, sjinfo->min_righthand) ||
                (sjinfo->jointype == JOIN_FULL && bms_overlap(relids, sjinfo->min_lefthand))) {
                /* yes; have we included all its rels in relids? */
                if (!bms_is_subset(sjinfo->min_lefthand, relids) || !bms_is_subset(sjinfo->min_righthand, relids)) {
                    /* no, so add them in */
                    relids = bms_add_members(relids, sjinfo->min_lefthand);
                    relids = bms_add_members(relids, sjinfo->min_righthand);
                    outerjoin_delayed = true;
                    /* we'll need another iteration */
                    found_some = true;
                }
                /* track all the nullable rels of relevant OJs */
                nullable_relids = bms_add_members(nullable_relids, sjinfo->min_righthand);
                if (sjinfo->jointype == JOIN_FULL)
                    nullable_relids = bms_add_members(nullable_relids, sjinfo->min_lefthand);
                /* set delay_upper_joins if needed */
                if (is_pushed_down && sjinfo->jointype != JOIN_FULL && bms_overlap(relids, sjinfo->min_lefthand))
                    sjinfo->delay_upper_joins = true;
            }
        }
    } while (found_some);

    /* identify just the actually-referenced nullable rels */
    nullable_relids = bms_int_members(nullable_relids, *relids_p);

    /* replace *relids_p, and return nullable_relids */
    bms_free_ext(*relids_p);
    *relids_p = relids;
    *nullable_relids_p = nullable_relids;
    return outerjoin_delayed;
}

/*
 * check_equivalence_delay
 *		Detect whether a potential equivalence clause is rendered unsafe
 *		by outer-join-delay considerations.  Return TRUE if it's safe.
 *
 * The initial tests in distribute_qual_to_rels will consider a mergejoinable
 * clause to be a potential equivalence clause if it is not outerjoin_delayed.
 * But since the point of equivalence processing is that we will recombine the
 * two sides of the clause with others, we have to check that each side
 * satisfies the not-outerjoin_delayed condition on its own; otherwise it might
 * not be safe to evaluate everywhere we could place a derived equivalence
 * condition.
 */
static bool check_equivalence_delay(PlannerInfo* root, RestrictInfo* restrictinfo)
{
    Relids relids;
    Relids nullable_relids;

    /* fast path if no special joins */
    if (root->join_info_list == NIL)
        return true;

    /* must copy restrictinfo's relids to avoid changing it */
    relids = bms_copy(restrictinfo->left_relids);
    /* check left side does not need delay */
    if (check_outerjoin_delay(root, &relids, &nullable_relids, true))
        return false;

    /* and similarly for the right side */
    relids = bms_copy(restrictinfo->right_relids);
    if (check_outerjoin_delay(root, &relids, &nullable_relids, true))
        return false;

    return true;
}

/*
 * check_redundant_nullability_qual
 *	  Check to see if the qual is an IS NULL qual that is redundant with
 *	  a lower JOIN_ANTI join.
 *
 * We want to suppress redundant IS NULL quals, not so much to save cycles
 * as to avoid generating bogus selectivity estimates for them.  So if
 * redundancy is detected here, distribute_qual_to_rels() just throws away
 * the qual.
 */
static bool check_redundant_nullability_qual(PlannerInfo* root, Node* clause)
{
    Var* forced_null_var = NULL;
    Index forced_null_rel;
    ListCell* lc = NULL;

    /* Check for IS NULL, and identify the Var forced to NULL */
    forced_null_var = find_forced_null_var(clause);
    if (forced_null_var == NULL)
        return false;
    forced_null_rel = forced_null_var->varno;

    /*
     * If the Var comes from the nullable side of a lower antijoin, the IS
     * NULL condition is necessarily true.
     */
    foreach (lc, root->join_info_list) {
        SpecialJoinInfo* sjinfo = (SpecialJoinInfo*)lfirst(lc);

        if (sjinfo->jointype == JOIN_ANTI && bms_is_member(forced_null_rel, sjinfo->syn_righthand))
            return true;
    }

    return false;
}

/*
 * distribute_restrictinfo_to_rels
 *	  Push a completed RestrictInfo into the proper restriction or join
 *	  clause list(s).
 *
 * This is the last step of distribute_qual_to_rels() for ordinary qual
 * clauses.  Clauses that are interesting for equivalence-class processing
 * are diverted to the EC machinery, but may ultimately get fed back here.
 */
void distribute_restrictinfo_to_rels(PlannerInfo* root, RestrictInfo* restrictinfo)
{
    Relids relids = restrictinfo->required_relids;
    RelOptInfo* rel = NULL;

    switch (bms_membership(relids)) {
        case BMS_SINGLETON:

            /*
             * There is only one relation participating in the clause, so it
             * is a restriction clause for that relation.
             */
            rel = find_base_rel(root, bms_singleton_member(relids));

            /* Add clause to rel's restriction list */
            rel->baserestrictinfo = lappend(rel->baserestrictinfo, restrictinfo);
            /* Update security level info */
            rel->baserestrict_min_security = Min(rel->baserestrict_min_security, restrictinfo->security_level);
            break;
        case BMS_MULTIPLE:

            /*
             * The clause is a join clause, since there is more than one rel
             * in its relid set.
             */
            /*
             * Check for hashjoinable operators.  (We don't bother setting the
             * hashjoin info except in true join clauses.)
             */
            check_hashjoinable(restrictinfo);

            /*
             * Add clause to the join lists of all the relevant relations.
             */
            add_join_clause_to_rels(root, restrictinfo, relids);
            break;
        default:

            /*
             * clause references no rels, and therefore we have no place to
             * attach it.  Shouldn't get here if callers are working properly.
             */
            ereport(ERROR,
                (errmodule(MOD_OPT),
                    errcode(ERRCODE_OPTIMIZER_INCONSISTENT_STATE),
                    (errmsg("cannot cope with variable-free clause when distribute restrictinfo to rels"))));
            break;
    }
}

/*
 * process_implied_equality
 *	  Create a restrictinfo item that says "item1 op item2", and push it
 *	  into the appropriate lists.  (In practice opno is always a btree
 *	  equality operator.)
 *
 * "qualscope" is the nominal syntactic level to impute to the restrictinfo.
 * This must contain at least all the rels used in the expressions, but it
 * is used only to set the qual application level when both exprs are
 * variable-free.  Otherwise the qual is applied at the lowest join level
 * that provides all its variables.
 *
 * "nullable_relids" is the set of relids used in the expressions that are
 * potentially nullable below the expressions.  (This has to be supplied by
 * caller because this function is used after deconstruct_jointree, so we
 * don't have knowledge of where the clause items came from.)
 *
 * "both_const" indicates whether both items are known pseudo-constant;
 * in this case it is worth applying eval_const_expressions() in case we
 * can produce constant TRUE or constant FALSE.  (Otherwise it's not,
 * because the expressions went through eval_const_expressions already.)
 *
 * Note: this function will copy item1 and item2, but it is caller's
 * responsibility to make sure that the Relids parameters are fresh copies
 * not shared with other uses.
 *
 * This is currently used only when an EquivalenceClass is found to
 * contain pseudoconstants.  See path/pathkeys.c for more details.
 */
void process_implied_equality(PlannerInfo* root, Oid opno, Oid collation, Expr* item1, Expr* item2, Relids qualscope,
    Relids nullable_relids, Index security_level, bool below_outer_join, bool both_const)
{
    Expr* clause = NULL;

    /*
     * Build the new clause.  Copy to ensure it shares no substructure with
     * original (this is necessary in case there are subselects in there...)
     */
    clause = make_opclause(opno,
        BOOLOID, /* opresulttype */
        false,   /* opretset */
        (Expr*)copyObject(item1),
        (Expr*)copyObject(item2),
        InvalidOid,
        collation);

    /* If both constant, try to reduce to a boolean constant. */
    if (both_const) {
        clause = (Expr*)eval_const_expressions(root, (Node*)clause);

        /* If we produced const TRUE, just drop the clause */
        if (clause && IsA(clause, Const)) {
            Const* cclause = (Const*)clause;

            AssertEreport(cclause->consttype == BOOLOID, MOD_OPT, "bool is required.");
            if (!cclause->constisnull && DatumGetBool(cclause->constvalue))
                return;
        }
    }

    /*
     * Push the new clause into all the appropriate restrictinfo lists.
     */
    distribute_qual_to_rels(root,
        (Node*)clause,
        true,
        below_outer_join,
        JOIN_INNER,
        security_level,
        qualscope,
        NULL,
        NULL,
        nullable_relids,
        NULL,
        false);
}

void process_implied_quality(PlannerInfo* root, Node* node, Relids relids, bool below_outer_join)
{
    Relids relids_copy = bms_copy(relids);
    ListCell* cell = NULL;
    RelOptInfo* rel = NULL;
    int relid = -1;
    bool found = false;

    Assert(BMS_SINGLETON == bms_membership(relids_copy));

    relid = bms_first_member(relids_copy);
    bms_free_ext(relids_copy);

    if (relid < 0) {
        ereport(ERROR, (errcode(ERRCODE_INVALID_PARAMETER_VALUE), errmsg("relid must not be less than zero.")));
    }
    rel = root->simple_rel_array[relid];

    Assert(rel != NULL && rel->reloptkind == RELOPT_BASEREL);

    foreach (cell, rel->baserestrictinfo) {
        RestrictInfo* rinfo = (RestrictInfo*)lfirst(cell);

        if (equal(node, rinfo->clause)) {
            found = true;

            break;
        }
    }

    if (found)
        return;

    distribute_qual_to_rels(
        root, node, true, below_outer_join, JOIN_INNER, root->qualSecurityLevel, relids, NULL, NULL, NULL, NULL, FALSE);
}

/*
 * build_implied_join_equality --- build a RestrictInfo for a derived equality
 *
 * This overlaps the functionality of process_implied_equality(), but we
 * must return the RestrictInfo, not push it into the joininfo tree.
 *
 * Note: this function will copy item1 and item2, but it is caller's
 * responsibility to make sure that the Relids parameters are fresh copies
 * not shared with other uses.
 *
 * Note: we do not do initialize_mergeclause_eclasses() here.  It is
 * caller's responsibility that left_ec/right_ec be set as necessary.
 */
RestrictInfo* build_implied_join_equality(
    Oid opno, Oid collation, Expr* item1, Expr* item2, Relids qualscope, Relids nullable_relids, Index security_level)
{
    RestrictInfo* restrictinfo = NULL;
    Expr* clause = NULL;

    /*
     * Build the new clause.  Copy to ensure it shares no substructure with
     * original (this is necessary in case there are subselects in there...)
     */
    clause = make_opclause(opno,
        BOOLOID, /* opresulttype */
        false,   /* opretset */
        (Expr*)copyObject(item1),
        (Expr*)copyObject(item2),
        InvalidOid,
        collation);

    /*
     * Build the RestrictInfo node itself.
     */
    restrictinfo = make_restrictinfo(clause,
        true,             /* is_pushed_down */
        false,            /* outerjoin_delayed */
        false,            /* pseudoconstant */
        security_level,   /* security_level */
        qualscope,        /* required_relids */
        NULL,             /* outer_relids */
        nullable_relids,  /* nullable_relids */
        false); 

    /* Set mergejoinability/hashjoinability flags */
    check_mergejoinable(restrictinfo);
    check_hashjoinable(restrictinfo);

    return restrictinfo;
}

/*****************************************************************************
 *
 *	 CHECKS FOR MERGEJOINABLE AND HASHJOINABLE CLAUSES
 *
 *****************************************************************************/
/*
 * check_mergejoinable
 *	  If the restrictinfo's clause is mergejoinable, set the mergejoin
 *	  info fields in the restrictinfo.
 *
 *	  Currently, we support mergejoin for binary opclauses where
 *	  the operator is a mergejoinable operator.  The arguments can be
 *	  anything --- as long as there are no volatile functions in them.
 */
static void check_mergejoinable(RestrictInfo* restrictinfo)
{
    Expr* clause = restrictinfo->clause;
    Oid opno;
    Node* leftarg = NULL;
    Node* rightarg = NULL;
    if (restrictinfo->pseudoconstant)
        return;
    if (!is_opclause(clause))
        return;
    if (list_length(((OpExpr*)clause)->args) != 2)
        return;

    opno = ((OpExpr*)clause)->opno;
    leftarg = (Node*)linitial(((OpExpr*)clause)->args);
    rightarg = (Node*)lsecond(((OpExpr*)clause)->args);
    /* 
     * For data of type set, using the merge join plan will result in inconsistent outcomes.
     */
    if (nodeTag(leftarg) == T_Var) {
        Var* leftCol = (Var*)leftarg;
        if (type_is_set(leftCol->vartype)) {
            return;
        }
    }
    if (nodeTag(rightarg) == T_Var) {
        Var* rightCol = (Var*)rightarg;
        if (type_is_set(rightCol->vartype)) {
            return;
        }     
    }
    if (op_mergejoinable(opno, exprType(leftarg)) && !contain_volatile_functions((Node*)clause))
        restrictinfo->mergeopfamilies = get_mergejoin_opfamilies(opno);

    /*
     * Note: op_mergejoinable is just a hint; if we fail to find the operator
     * in any btree opfamilies, mergeopfamilies remains NIL and so the clause
     * is not treated as mergejoinable.
     */
}

/*
 * check_hashjoinable
 *	  If the restrictinfo's clause is hashjoinable, set the hashjoin
 *	  info fields in the restrictinfo.
 *
 *	  Currently, we support hashjoin for binary opclauses where
 *	  the operator is a hashjoinable operator.	The arguments can be
 *	  anything --- as long as there are no volatile functions in them.
 */
void check_hashjoinable(RestrictInfo* restrictinfo)
{
    Expr* clause = restrictinfo->clause;
    Oid opno;
    Node* leftarg = NULL;

    if (restrictinfo->pseudoconstant)
        return;
    if (!is_opclause(clause))
        return;
    if (list_length(((OpExpr*)clause)->args) != 2)
        return;

    opno = ((OpExpr*)clause)->opno;
    leftarg = (Node*)linitial(((OpExpr*)clause)->args);
    if (op_hashjoinable(opno, exprType(leftarg)) && !contain_volatile_functions((Node*)clause))
        restrictinfo->hashjoinoperator = opno;
}

/* check_plan_correlation
 *	check if there's any subplan expr in expr node, and then
 *	set correlated flag for planner infos
 *
 * Parameters:
 *	@in root: Plannerinfo struct for current query level
 *	@in expr: expression to find correlated info between different level
 */
void check_plan_correlation(PlannerInfo* root, Node* expr)
{
    if (!IS_STREAM_PLAN) {
        return;
    }

    List* param_expr = check_subplan_expr(expr, true);

    ListCell* lc = NULL;
    ListCell* lc2 = NULL;

    /* traverse all the subplan exprs to find correlated level */
    foreach (lc, param_expr) {
        PlannerInfo* tmp_root = root->parent_root;
        Param* param = (Param*)lfirst(lc);
        /* subplan expr */
        if (IsA(param, Param)) {
            /* find the expr reference level */
            while (tmp_root != NULL) {
                foreach (lc2, tmp_root->plan_params) {
                    PlannerParamItem* item = (PlannerParamItem*)lfirst(lc2);
                    if (item->paramId == param->paramid) {
                        if (STREAM_RECURSIVECTE_SUPPORTED && root->is_under_recursive_cte) {
                            /*
                             * MPP With-Recursive
                             *
                             * For correlated CteSubLink, in case of correlation is
                             * conencted to a recursive CTE, we need mark the parm
                             * item flag to tell the upper generate replicate plan
                             ***/
                            if (!IsA(item->item, Var)) {
                                errno_t sprintf_rc = sprintf_s(u_sess->opt_cxt.not_shipping_info->not_shipping_reason,
                                    NOTPLANSHIPPING_LENGTH,
                                    "With-Recursive is correlated with unsupported decorrelation varno");
                                securec_check_ss_c(sprintf_rc, "\0", "\0");
                                mark_stream_unsupport();
                            }

                            RangeTblEntry* rte = rt_fetch(((Var*)item->item)->varno, tmp_root->parse->rtable);
                            rte->correlated_with_recursive_cte = true;
                        }
                        break;
                    }
                }
                if (lc2 != NULL)
                    break;

                tmp_root = tmp_root->parent_root;
            }

            /* we should set correlated flag from referece level to upper level */
            if (tmp_root != NULL) {
                PlannerInfo* tmp_root2 = root;
                while (tmp_root2 != tmp_root) {
                    if (!tmp_root2->is_correlated)
                        tmp_root2->is_correlated = true;
                    tmp_root2 = tmp_root2->parent_root;
                }
            }
        }
    }

    if (param_expr != NULL) {
        list_free_ext(param_expr);
    }
}
